The present invention relates to an optical sensor means according to the preamble of claim 1.
Such sensor means have a plurality of linearly arranged lightsensitive surfaces. In order to obtain a good resolution, the lightsensitive surfaces or sensor units, which are conventionally called pixels are closely juxtaposed. For example, 4096 pixels can be spaced by 10 .mu.m. The resolution attainable with this arrangement is also 10 .mu.m. However, in certain circumstances such a resolution is not satisfactory. Admittedly the resolution can be improved with the aid of an upstream connected optical system, but this leads to it no longer being possible to cover a range of 4096.times.10 .mu.m, i.e. approximately 4 cm and instead the range is smaller by the magnification factor.
In order to achieve an improved resolution without using complicated and costly optical aids, several sensors can be displaced in parallel with one another and conventionally CCD sensors are used. They have a width of at least several mm, so that there is a risk of parallax errors, if several sensors are juxtaposed. In addition, with such sensors, a significant improvement to the resolution would mean an unacceptable time expenditure.
Another possibility of increasing the resolution consists of using only one CCD line sensor and to periodically move the same backwards and forwards e.g. by 5 .mu.m, scanning taking place in each end position. However, it is then necessary to have very accurate and therefore very complicated mechanical drive means and this type of scanning also reduces the scanning rate. This can lead to speed problems in the case of time-critical applications, because one CCD sensor supplies one information per pixel in each scanning interval.